The present invention relates generally to semiconductor devices and the manufacturing methodology thereof; and, more particularly, the invention relates to technologies usefully applicable to high-density mountable semiconductor devices with tape carrier package (TCP) structures along with fabrication methods thereof.
In recent years, as portable or handheld electronic equipment, of reduced shape and thickness, and yet with much increased functionalities, is being developed for mass production, TCP technologies are becoming more and more important in the manufacture of solid-state integrated circuit (IC) packages for use in highly advanced electronic equipment with respect to the enhanced mountability of thickness-reduced or xe2x80x9cthinxe2x80x9d electronics components and also to the ability to increase the number of package pins.
The TCP is a package including a tape carrier having a plurality of conductive leads formed thereon in a repeated pattern, wherein a semiconductor chip is placed on or in the tape carrier with its electrode pads lamination-contacted with corresponding ones of the carrier leads for electrical interconnection therebetween, the semiconductor chip being sealed by a sealing resin material or the like.
Prior known TCPs typically have been designed so that the semiconductor chip being used is greater in thickness than the tape carrier, which would result in an increase in the mounting height of a multilayer tape structure wherein multiple unitary tape carriers are laminated on one another. One prior art approach to mount-height reduction has been described, for example, in Japanese Patent Application Laid-Open No. 63(1985)-52431 (xe2x80x9cJP-A-63-52431xe2x80x9d), which discloses a tape carrier for use with a certain semiconductor chip having its bottom or back surface cut away. Another approach is found in JP-A-5(1993)-291218, which discloses therein a technique for making both the semiconductor chip and the tape carrier thinner at the same time.
Another TCP structure is also known which includes a specific frame structure, called a xe2x80x9cstiffenerxe2x80x9d in the semiconductor device art. The stiffener is provided around a semiconductor chip with its back surface in contact with a heat release member known as a xe2x80x9cheat spreader.xe2x80x9d In this TCP, a tape carrier is mounted on the stiffener for providing a junction between one end of its lead and the semiconductor chip while simultaneously providing a bump electrode at the other end of such lead. In this case the resultant TCP structure suffers from an excessive increase in thickness, which would result in an inability to achieve the desired multilayer structures.
Still another TCP structure has been found through analysis by the present inventors, which TCP structure is designed to employ a semiconductor chip that is thinner than a tape carrier having an opening called a xe2x80x9cdevice hole.xe2x80x9d The xe2x80x9cthinxe2x80x9d semiconductor chip is disposed in the tape carrier""s device hole with its back surface being substantially at the same level as or coplanar with the bottom surface of the tape carrier. The principal surface and sidewalls of such a semiconductor chip are coated with a chosen sealing resin material. Unfortunately, this TCP structure has encountered a problem in that the semiconductor chip can warp after completion of the sealing processes due to the fact that only its principal surface and sidewalls are partly subject to sealing by use of the seal resin. To this end, this TCP structure must be designed to employ an extra hard or rigid plate for use in eliminating the occurrence of chip cracks in the back surface of the semiconductor chip. However, this does not come without an additional problem in that the resultant TCP is increased in thickness, thereby discouraging experts in the art from attempting to use such a xe2x80x9cthickxe2x80x9d TCP to attain a desired multilayer structure. While a structure with a seal plate provided on the seal resin is known, this also suffers from the TCP thickness increase problem, and is not suitable for use as a multilayer structure. Additionally, a thin package structure using a film substrate with its lower surface coplanar with the back surface of a chip has been disclosed, for example, in JP-A-60(1985)-106153.
According to currently available technologies recognized by the present inventors, the semiconductor chips are thinner than the tape carriers in most TCP structures. In cases where such TCPs are laminated on one another to form a multilayer structure, the outer leads are typically machined to have a so-called xe2x80x9cgull-wingxe2x80x9d shape for elimination of unwanted contact of a semiconductor chip with its associated mounting board, such as a printed circuit board. In addition, in case plural ones are to be mounted in the direction along the thickness of the TCP, a specific parts-mount scheme must be employed which includes the steps of pre-fabricating those TCPs with outer leads of different lengths, and, after completion of various lead machining processes, rearranging the layout in a way such that those with low mount heights are located at lower levels, whereas the remaining ones with higher mount levels are at upper levels. In this case, however, different tape carriers are used to accomplish the intended overlap mounting with outer leads different in size from one another. This in turn calls for the use of a variety of types of tape carriers as well as various molding die tools, which would result in an increase in production cost therefor. Additionally, the TCP lamination mount technique is disclosed in JP-A-64(1989)-71162, for example.
It is therefore an object of the present invention to provide a technique for enabling the manufacture of a semiconductor device with a TCP structure which is high in reliability.
Another object of this invention is to provide a technique for enabling fabrication of a thin small-size semiconductor device with TCP structures offering high-density mountability and enhanced reliability, while reducing costs.
These and other objects, features and advantages of the invention will be apparent from the following more particular description of various preferred embodiment of the invention, as illustrated in the accompanying drawings.
A semiconductor device in accordance with the present invention is specifically arranged to include a semiconductor chip disposed in a device hole provided in a tape carrier with one end of a lead on said tape carrier being electrically connected to an external terminal of said semiconductor chip, wherein said semiconductor chip is smaller in thickness than said tape carrier, and wherein said semiconductor chip is sealed by a seal resin material to allow a principal surface and a back surface of said semiconductor chip to be coated therewith. Whereby, it becomes possible to reduce any possible stress that the semiconductor chip can receive from the principal surface and rear surface thereof. Also, the semiconductor device of this invention is such that said semiconductor chip is disposed on a stress neutral plane extending parallel to the principal surface of said semiconductor chip at the position along a thickness of said tape carrier. This makes it possible to allow the semiconductor chip to be placed at a location whereat the stress receivable from the TCP is kept minimal. Even in the event any external force is applied causing the TCP to deform as a whole, the semiconductor chip may be subjected to a minimal stress. It is also possible to suppress the occurrence of warp in the overall TCP structure due to bimetal effects, which may in turn enable noticeable reduction of risks of chip cracks and/or connection failures during mounting assembly procedures of the semiconductor device.
In addition, the semiconductor device of the instant invention is such that a passage for use in seal resin injection is formed at part of said tape carrier thereby causing said device hole to be coupled to a gate of a metal mold structure used during formation of said seal resin. With such an arrangement, it is possible to successfully inject the seal resin so that resin uniformly covers both the principal surface and rear surface of the semiconductor chip, which in turn makes it possible to greatly suppress the formation of voids and/or traps in the seal resin.
In addition, the semiconductor device of this invention is such that said tape carrier has an air exhaust port formed to allow the device hole of said tape carrier to be coupled to an air vent of the metal mold structure for use during formation of said seal resin. It is thus possible to suppress any residual air inside of the seal resin coating both the principal surface and rear surface of the semiconductor chip, which in turn enables significant reduction in the creation of voids and/or traps within the seal resin. Accordingly, the semiconductor device may be further improved in reliability.
In addition, the semiconductor device of the invention is such that an electroplated metal layer is formed at part of a surface of said tape carrier in close proximity to said passage for seal resin injection, the part being brought into contact with the seal resin during formation of said seal resin coating. Whereby, it is possible to reduce the adhesive bondability between the seal resin and tape carrier, which in turn makes it possible to accelerate peel-off or debonding of the resin from the tape carrier during separation between the TCP and the sub-runner""s resin to be carried out after the resin seal process.
In addition, the semiconductor device of the invention is such that said semiconductor chip has its back surface polished by a spin etching technique. This may permit reduction in the thickness of the semiconductor chip. Simultaneously, it is possible to make the rear surface of the semiconductor chip smoother thereby enabling the semiconductor chip to offer a physically robust structure with enhanced resistivity to flexure/bending stresses while remaining hard-crackable.
In addition, a semiconductor device of the invention is arranged to have a multilayer package structure including a plurality of laminated tape carriers with a semiconductor chip which is smaller in thickness than each tape carrier being disposed in a device hole of each tape carrier, wherein one end of a lead provided to each of said plurality of laminated tape carriers is electrically connected to an external terminal of the semiconductor chip in the device hole of each tape carrier, wherein each semiconductor chip is coated with seal resin on both a principal surface and a back surface thereof, and wherein each of said laminated tape carriers has a common signal transmission lead and a power supply lead each being electrically connected to corresponding ones of other carriers to be externally drawn out as a connection terminal being electrically connected to a lead of a mounting board. With such an arrangement, it becomes possible to provide an improved semiconductor device of a thickness-reduced or thinner TCP structure, while increasing the mountability or packaging density of the semiconductor chips thereon.
In addition, the semiconductor device of the invention is arranged so that a connection hole is defined in each of said tape carriers laminated on one another, thereby causing part of said lead to be exposed while permitting part of said lead to project into said connection hole, and also a conductive material is buried in the connection hole to allow a common signal transmission lead and a power supply lead of each said tape carrier to be electrically connected together. Whereby, it is possible to make sure that the lead is in contact with the conductive material within said connection hole, which in turn makes it possible to improve the connection reliability within such connection hole.
In addition, the semiconductor device of the invention is such that a connection hole is defined in each of said plurality of tape carriers laminated on one another, thereby causing part of said lead to be exposed, while applying electroplating to the inside of the connection hole, thus allowing each of a common signal transmission lead and a power supply lead of each said tape carrier to be electrically connected to corresponding ones of the remaining carriers. Whereby, a conductive section is formed within the connection hole by use of currently available long-use electroplating techniques, which in turn enables the conductive section to be formed inside of the connection hole with minimized complexity.
In addition, the semiconductor device of the invention is such that a connection hole is defined in each of said plurality of tape carriers laminated on one another thereby causing part of said lead to be exposed while inserting a conductive pin into the connection hole thus allowing each of a common signal transmission lead and a power supply lead of each said tape carrier to be electrically connected to corresponding ones of remaining carriers with one end of said conductive pin being extended from a mounting surface of said multilayer package as said connection terminal. Whereby, it becomes possible to improve the mechanical strength or robustness of the multilayer TCP structure while reducing costs.
In addition, the semiconductor device of the invention is arranged to allow a remaining end of a lead of each of said plurality of tape carriers laminated on one another to extend from an outer periphery of each tape carrier to provide a projected lead portion which is bent for lamination with others to thereby permit electrical connection between a common signal line of each of said plurality of laminated tape carriers and corresponding ones of other tape carriers and also between a power supply line of each tape carrier and corresponding ones of other carriers. With the outer lead deformed in structure, it is possible to increase the mechanical strength of the lead configuration while reducing the complexity and costs. It is also possible to attain enhanced absorbability of thermal expansivity differences between the multilayered TCP and the mounting board.
In addition, the semiconductor device of the invention is arranged to prevent a bump electrode from contact with a certain external terminal of said semiconductor chip to permit modification of a connection route between said semiconductor chip and lead. Whereby, it is possible by use of tape carriers of the singular type to flexibly accommodate any possible modifications or alterations as to connection routes for different signal transmission paths.
In addition, a semiconductor device manufacturing method in accordance with the invention include the steps of:
(a) defining a connection opening or hole in said tape carrier to allow part of said lead to be exposed from the inside wall surface;
(b) burying conductive paste inside of said tape carrier;
(c) laminating multiple tape carriers each similar to said tape carrier on one another while causing said connection hole to remain uniform in formation position among them to thereby form a multilayer package; and
(d) applying thermal processing to the resultant multilayer package after completion of said lamination process step to thereby allow conductive paste components residing inside of the connection holes of respective ones of said tape carriers to become integral together. Whereby, it is possible to permit unitary packages to be contacted together without having any adhesive layer sandwiched between adjacent ones of them.
In addition, the method of manufacture of the semiconductor device of the invention includes the steps of:
(a) laminating said unitary packages on one another using an adhesive to form a multilayer package;
(b) burying a conductive paste within a connection hole as defined in each tape carrier of said multilayer package; and
(c) applying thermal processing to said multilayer package. Whereby, it becomes possible to dispose adjacent unitary packages in contact with each other by use of an adhesive layer constituting the unitary packages, which in turn makes it possible to manufacture the intended multilayer TCP without an increase in the number of process steps in the manufacture thereof.
In addition, the semiconductor device manufacturing method of the invention is such that external terminals of said semiconductor chip are disposed in contact with leads by a single-point bonding technique while preventing a certain external terminal of said external terminals from contact with a specified lead. Whereby, it is possible by using tape carriers of the same type to accommodate any possible connection route modifications with increased flexibility.
In addition, a method of manufacturing a semiconductor device also incorporating the principles of the invention includes the steps of:
(a) preparing a tape carrier of a specified thickness with leads disposed around said device hole;
(b) preparing a semiconductor chip which is smaller in thickness than said semiconductor chip and having more than one external terminal;
(c) disposing said semiconductor chip which is thinner than said tape carrier within the device hole of said tape carrier and then electrically connecting the external terminal of said semiconductor chip to one end of said lead; and
(d) after lamination of a plurality of tape carriers each with said external terminal electrically connected to the lead, sealing respective semiconductor chips disposed within device holes of respective tape carriers using a seal resin at one time. Whereby, it becomes possible to reduce in number the process steps required in the manufacture of the multilayer TCP structure. It is also possible to increase or maximize the mechanical strength while improving the resistivity against humidity because of the fact that no gap spaces are formed between tape layers due to integral formation of the seal resin for use in sealing multiple semiconductor chips together.